SPECC1 (sperm antigen with calponin homology and coiled-coil domains 1) is a gene located on chromosome 17 that encodes proteins involved in actin cytoskeleton organization and microtubule organization. The gene is primarily characterized through its circular RNA form (circSPECC1), which functions as a regulatory molecule in multiple cancer contexts. CircSPECC1 acts as a competing endogenous RNA (ceRNA) or "sponge" that sequesters microRNAs, preventing their interactions with target mRNAs. In glioblastoma, circSPECC1 encodes a novel 415-amino acid protein (SPECC1-415aa) that suppresses tumor progression and restores temozolomide sensitivity by inhibiting EGFR and AKT phosphorylation 1. In hepatocellular carcinoma, circSPECC1 sponges miR-33a to regulate TGFβ2 expression and autophagy under oxidative stress 2. In gastric cancer, circSPECC1 enhances miR-526b inhibition of the KDM4A/YAP1 pathway, suppressing proliferation and invasion 3. Conversely, in prostate cancer, circSPECC1 promotes epithelial-mesenchymal transition and cell proliferation 4. In age-related macular degeneration, circSPECC1 deficiency leads to oxidative stress-induced ferroptosis in retinal pigment epithelium; circSPECC1 sponges miR-145-5p to protect against retinal degeneration 5. Additionally, SPECC1 was identified as a fusion partner with NUTM1 in rare pulmonary NUT carcinoma 6. These diverse roles suggest SPECC1 functions as a regulatory hub with context-dependent tumor-suppressive or tumor-promoting effects.